如何在（app.config）中的connectionString使用应用程序数据 [英] How to use Application Data in an (App.config) connectionString

问题描述

我有在我wan't在一些地方保存在％APPDATA％目录中的项目的SQL Server CE数据库。不过，我不能找到一种方法，使连接字符串中的应用程序数据路径的引用（在App.config）

I've got an SQL Server CE database in a project that I wan't to store somewhere in the %AppData% directory. However I can't find a way to make a reference to the Application Data path in the connection string (in the App.Config)

<?xml version="1.0"?>
<configuration>
  <configSections>
  </configSections>
  <connectionStrings>
    <add name="EntityConnectionString" connectionString="metadata=res://*/EntityModel.csdl|res://*/EntityModel.ssdl|res://*/EntityModel.msl;provider=System.Data.SqlServerCe.3.5;provider connection string=&quot;Data Source=|ApplicationData|\Entities.sdf&quot;" providerName="System.Data.EntityClient"/>
  </connectionStrings>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup>
</configuration>

到目前为止，我了解到：％APPDATA％，不支持并使用设置类（如建议）将无法正常工作或者（设置类不是在异常已经抛出时构造）。

So far I learned that: %APPDATA% is not supported and using the settings class (like suggested) won't work either (the settings class isn't constructed at the time the exception is already thrown).

是否有可能使用的应用程序数据文件夹（或其他？在ConnectionString属性（在App.config特殊的文件夹））

Is it possible to use the application data folder (or another special folder) in the connectionString property (in the App.Config)?

请注意：好像我在寻找一个解决方案来修改连接字符串（代码）尽早而非本地App.Config中的解决方案

Note: it seems like I'm searching for an solution to modify the connection string (in code) as early as possible rather than an native App.Config solution.

推荐答案

使用您的自定义生成的环境变量支持：

Use your custom build environment variable support:

让你有：

<connectionStrings>
    <add name="My" connectionString="..;Data Source=|%AppData%|\Entities.sdf;.." />
</connectionStrings>

的

你可以使用：

The you can use:

using System.Configuration; // requires reference to System.Configuration.dll

ConfigurationManager.ConnectionStrings["EntityConnectionString"].ConnectionString.Replace("%AppData%", Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);

接下来，您就可以支持多种环境变量：

Next way you can support several environment variables:

var vars = new Dictionary<string, string>
{
    { "%AppData%", Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
    { "%Temp%", Environment.GetFolderPath(SpecialFolder.Temp) },
    // etc..
    { "%YourNonStandardVar", "YourNonStandartPath" }
};

var result = ConfigurationManager.ConnectionStrings["YourString"].ConnectionString
foreach (var v in vars)
    result = result.Replace(v.Key, v.Value);

这篇关于如何在（app.config）中的connectionString使用应用程序数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！